Presently, modifying the appearance of or treating the human skin with liquid substances or powders has normally been accomplished by topographical application to the surface of the skin. For example, prior applications have been used to attempt to eliminate cornified portions of the skin in both chemical and nutritional ways, but cornification is a complicated biological phenomenon as well as being a problem, primarily occurring in the aging process. With the known types of application the substance is only temporarily retained as such substances are readily removed by perspiration, washing, unintentional contact with foreign materials and various weather conditions, making it necessary to reapply the substances on a daily or more frequent, basis. Further, any desired depth of penetration into the skin has been difficult to accurately control. Thus, there are major problems in the convenience, effectiveness, and effort in conventional applications.
Also, needles are commonly used to inject drugs, such as insulin, interferon, and pain killers, into the skin or flesh of patients, but these conventionally penetrate considerably deeper than necessary and cannot be controlled reliably as to the depth of penetration. Furthermore, they often cause pain to the patient.
Thus, there are major problems in convenience, effectiveness and effort in applying functional substances using these known types of application.